1. Field of the Invention
The invention relates to a conveyor for transporting work pieces in a press, in particular a press line or multiple-die press, from a first station to a second station adjacent to the first station, comprising at least one lateral beam arranged on a side of the press, essentially extending parallel to a transport direction of the conveyor, at least one bar having grippers for gripping the work piece to be transported, whereby the bar is attached to the lateral beam in such a way that it is movable along a longitudinal extension of the beam, and for each lateral beam an assembly for supporting the lateral beam.
2. Description of the Related Art
An important step of the manufacture of components made of sheet metal is the forming step. Sheet metal parts are formed in a press, such as a hydraulic, hydroforming, mechanical, electrical or pneumatic press, typically including an upper die and a corresponding lower die. The dies are moved against each other, and thereby the work piece arranged in the work space between the dies is formed. The form of the dies determines the impact on the work piece and therefore the resulting form. Usually, a succession of forming steps using differently shaped dies is necessary until the desired form of the sheet metal part is obtained. To achieve this in an expedient way, a plurality of presses is arranged successively to form a press line, or a press is employed that includes multiple dies. On one hand, the capacity of the press line or multiple-die press is determined by the capacity of the press, i.e. the time required for carrying out one forming operation. On the other hand however, the capacity is significantly depending on the efficiency of the transport of the work pieces from one press station to the next one. It is therefore important to employ a fast transfer system for automatically transporting work pieces from one press station to the next one.
The German patent application DE 100 10 079 A1 (Müller-Weingarten) refers to a conveyor attached to a vertical support of a press. The conveyor comprises a vertical drive having two cogwheels independently acting on two vertical cograils. Both the cograils act on a third cogwheel arranged in between them, to which a pivotable arm is directly connected. By combining the vertical as well as the pivoting motion of the arm a work piece may be transported from a press station to the next one.
The European patent EP 0 850 709 B1 (Schuler) discloses a conveyor where a cross bar is attached on both its sides to guide-rod mechanisms. The rods of the mechanism are independently attached to vertically movable slides mounted to a vertical press support. By displacing the slides the cross bar is movable in a vertical as well as in a horizontal direction.
These conveyors only allow for a limited transport range that directly depends on the length of the pivotable arm or the guide rods, respectively.
The European patents EP 0 621 093 B1 (Müller-Weingarten) and EP 0 600 254 B1 (Schuler) as well as the US patent application US 2003/84701 A1 (Komatsu) refer to conveyors for a press line, where cross bars having grippers for gripping the work pieces extend between transport carriages arranged at both sides of the press. The transport carriages are independently movable on horizontal supporting rails extending parallel to the transport direction of the conveyor. Where the carriages of EP 0 621 093 B1 comprise a vertical drive for lifting and lowering the cross bar, the EP 0 600 254 B1 and US 2003/84701 A1 disclose supporting rails that are vertically movable.
In principle these conveyors allow for a transport range that is only limited by the length of the supporting rails. However, the construction of the conveyors is rather complex and the mass of the components that have to be moved in a horizontal and/or vertical direction during the transport process is large. Correspondingly, the achievable speed and efficiency is limited.